aiomysql executemany is very slow to insert about aiomysql HOT 4 OPEN

sql = "INSERT INTO table_a (field1, field2, ..) VALUES {}"

values_str = create_insert_values(tlis_schp)
conn = db_pool.connection()
cursor = conn.cursor()
cursor.execute(sql, values_str or ())

def create_insert_values(data):
    values_list = []
    for record in data:
        values = []
        for item in record:
            if isinstance(item, str):
                escaped_item = item.replace("'", "''")
                values.append(f"'{escaped_item}'")
            elif item is None or (isinstance(item, float) and math.isnan(item)):
                values.append("NULL")
            elif isinstance(item, datetime.datetime):
                values.append(f"'{item}'")
            elif isinstance(item, decimal.Decimal):
                values.append(f"'{item}'")
            elif isinstance(item, decimal.Decimal):
                values.append(f"'{item}'")
            else:
                values.append(str(item))
        values_str = f"({', '.join(values)})"
        values_list.append(values_str)
    return ',  '.join(values_list)